The invention has as its object an anti-catching system for protection against getting caught in automatically operable closures such as doors or windows, particularly of vehicles.
Various systems for protection against getting caught in automatically operable doors are known.
For example, it is known, especially in connection with elevator doors, to provide parallel to the closing path of the doors an electric eye which then reacts to an object or a person located between the doors and triggers a stop or reverse motion. However, such systems are not always reliable since electric eyes cannot be placed so that they will unfailingly detect every obstruction, except at considerable expenditure.
Moreover, there are systems in which the door motion is reversed in that when a door is being held there is formed in a pneumatic system actuating the door a certain pressure difference which triggers an appropriate control action if a predetermined threshold value is reached. With such systems, however, considerable counterpressure must usually be overcome by the person wedged in before the reversing motion is initiated, which is considered a nuisance and may also endanger a person so caught.
Finally, there are systems, especially on the doors of vehicles such as buses, trolleys, etc., where the rubber gaskets disposed along the door edges are provided with electric limit switches which trigger the control action for reversing the door motion when pressure is exerted on the rubber gasket. However, since these delicate limit switches are located at exposed points, such systems are apt to malfunction and therefore do not provide the desired security.